.TH lha_daemonctl 1 "18 May 2012" "TrueCL Commands"

.SH NAME
lha_diskhbctl \- Control / Send messages to Disk Heartbeats

.SH SYNOPSES
.TS
l l.
lha_diskhbctl	 \fB--msg\fP \fIMSG\fP [\fB--node\fP \fIN\fP] \fP] [\fB--timeout\fP \fIT\fP]
	[\fB--debug\fP|\fB--verbose\fP|\fB--quiet\fP|\fB--silent\fP] [\fB--lwidth\fP \fIW\fP]
.TE

.SH DESCRIPTION
The \fIlha_diskhbctl(1)\fP command is used to write messages to a disk heartbeat region 
and read any response received.

THIS UTILITY DOES NOT COMMUNICATE DIRECTLY WITH ANY OTHER NODES. The \fB--node\fP option
indicates which area of disk is written/read - no TCP/IP communication takes place with the node
itself.

Since each of the requests (or messages) requires writing to the raw disk device prior to doing
so the software will re-read the disk keys expected on the device to ensure it is indeed the
correct device. This slows the utility somewhat; a price to pay to remove the risk of it 
corrupting data if devices have been renamed.

Once written it will await for a response to appear in the region for that node to write to.
This is done by polling the content of the disk area (it clears it first before sending the
request).

.SH ARGUMENTS
.TP 8
--node
The name of the node to write the message to.
.TP
--msg
The message to write to the disk region for the node in question. Only a very limitde set of
requests are currently supported - see the \fBSUPPORTED MESSAGES\fP section below for more
details.
.TP
--timeout
The timeout to wait for a response. The default is 10 seconds.
.TP
--debug
Perform the actions and generate debug level output. This is not 
typically required and should only be done if problems in cluster 
management occur.
.TP
--verbose
Verbose mode generates a sensible amount of output to standard output to 
show the progress of the message delivery, polling and reading.
.TP
--quiet
This will only produce errors and warnings on the standard output device.
.TP
--silent
Only produce output if fatal errors occurs during disk message processing.
.TP
--lwidth
The width of the standard output. This will default to 80 if the width
of the standard output device cannot be determined. 

.SH SUPPORTED MESSAGES
Only a limited number of messages are currently supported. Further messages
are expected to be added over time.

.TP 12
CLEAN_STOP
Stop all running applications that are currently present on the node
communicated with.
.TP
ABORT_DAEMONS
Stops all running daemons on the node in question (core daemons rather than the
database service ones).
.TP
RUNNING_APPS
Returns a list of applications currently running on the node in question.
.TP
NODE_DOWN node
Used by nodes to indicate that 'node' should be marked as down.

.SH EXIT CODES
If the attempt to send a message via a disk write or a read failure occurs then the 
program will give a non-zero return code to indicate an error condition has occurred.

.SH AUTHOR
The TrueCL software was written by Simon Edwards, (C) 2006-2012, working
for Advantsys Computer Services Ltd - www.advantsys.co.uk.

.SH SEE ALSO
.BR clreq(1),
.BR lha_clusterd(1),
.BR lha_hbd(1),
.BR lha_lockd(1),
.BR lha_mond(1),
.BR lha_netd(1),
.BR lha_statd(1),
.BR lha_syncd(1),
.BR lha_netd(1).

.SH AVAILABILITY
This utility was specifically written under the GNU GPL license and as required
by such software comes with \fIno warranty or guarantee of any kind\fP. For
more information, please see the following page: truecl.advantsys.co.uk.

